My son installed XP Pro on my PC (His friends copy!!) . The 30 day time limit to register has expired. I purchased XP home edition upgrade, but cannot install it as I cannot get past the registration screen at the login stage. Can I install it from startup or not. Any help would be appreciated.

Cheers

the upgrade version you need a legit copy of a Windows O/S, as it's an upgrade that's all it will do

To add a bit to brain_damage's reply, since you have Pro installed, it's considered a "higher version" of the O/S. However, an Upgrade CD will install the full Home version from scratch.

As brain_damage stated, if you have a 95 or 98 CD, you could start fresh by booting with the Home CD, formatting the partition where Pro is installed (presumably C: ) to either FAT32 or NTFS (I would go with NTFS), and following the prompts for a new/fresh install. At some point you will be asked to insert a 95 or 98 CD (if I remember correctly, a Win2K CD is also OK) into the drive to prove you have a previous version of windows. Once this is done, it will tell you to insert the Home CD back into the drive and the install will proceed. The "previous" O/S (9x) does not need to be installed first.